Immune-complex induced prostaglandin production by monocytes of normal human subjects and cancer patients

Isolated cultures of mononuclear phagocytes from 12 humans (7 normal controls and 5 with cancer) produced prostaglandins (PGs) of the E series when stimulated with artificial immune complexes (HSA and anti-HSA). The amount of PGs produced by monocytes from breast cancer patients and macrophages from ascites fluid taken from patients with abdominal cancers was 4 fold that produced by blood monocytes from normal controls. Immune complex (IC) determinations from the serums of these humans (Raji cell method) showed that only patients in the advanced stages of the diseases, and none of the controls, had elevated levels of IC. In the presence of IC, there was noted a depression in the immune reactivity of mononuclear cell cultures, as determined by 3H thymidine uptake following stimulation with PHA, Con A and PWM. The depressed blastogenic response was not in all instances fully reversed by the addition of indomethacin or aspirin, indicating that PGs were not the only causative factor. It is concluded that mononuclear phagocytes elaborate immunosuppressive factors in response to stimulation by imune complexes. One of these factors is PGE. Further, this results in a homeostatic regulation which prevents damage from IC deposition and may be, in part, responsible for imunosuppression of cancer patients.